One field of application envisaged is that of the underwater transport of hydrocarbons, of water, of gas or of mixtures thereof. The underwater hydrocarbon drilling wells are linked to underwater installations bearing on the seabed by the rigid underwater pipes for conveying the hydrocarbons. The latter are generally extracted at a high temperature relative to the seabed temperature, and the temperature variations of the hydrocarbons or else the pressure variations, even the service outages, consequently cause thermal variations of the rigid pipe. So, the latter tends to elongate and then shrink. In order to avoid these elongations causing high axial stresses on the rigid pipe likely to cause uncontrolled lateral buckling of the rigid pipe, buckling points are initiated, step by step, where the pipe moves away laterally from its initial position. Since the lateral buckling zones are predefined by the designers, it is possible to give the rigid pipe improved characteristics offering a greater resistance to the great deformations imposed by the lateral buckling.
For this, the idea has been devised of installing transversely, step by step under the pipe, longitudinal supports, each formed by a tubular element of circular section so as to locally detach the rigid pipe from the seabed surface. The tubular element is covered with a coating facilitating the sliding of the rigid pipe. In this way, in the vicinity of the tubular element, the rigid pipe is free relative to the seabed and, consequently, the latter offers no resistance to it. Thus, when the rigid pipe tends to elongate because the hot transported fluid causes it to expand, an axial stress occurs, and it thus provokes a buckling of the rigid pipe at the transverse tubular element. In this way, the axial stress disappears.
Thus, prior to the installation of a rigid pipe from a surface vessel, tubular elements are deposited on the seabed, step by step and along the predetermined path of the rigid pipe. Then, the rigid pipe is deployed from the surface vessel on the seabed by guiding it for it to be able to come to bear exactly on the tubular elements, orthogonally.
Such a mode of implementation requires both a pre-installation of the tubular elements on the seabed and then a real accuracy in the laying of the rigid pipe. Consequently, the laying time can vary according to the weather and sea conditions.
Therefore, the problem which arises and that the present invention seeks to resolve is how to provide an underwater support device for the rigid underwater pipe that makes it possible to facilitate and shorten the laying time thereof and avoid any underwater intervention prior to the installation of the rigid pipe.